1. Field of the Invention
The present invention relates to an image reading apparatus and a driving apparatus.
2. Description of the Related Art
An image reading apparatus such as an image scanner reads an original on a platen by moving a reading sensor along the platen. The reading sensor is mounted on a moving unit such as a carriage. The moving unit is configured to be movable by being guided by a guide member extending in the scanning direction. As a mechanism for moving the moving unit, a rack and pinion mechanism is known to be used.
When using the rack and pinion mechanism, wobbling occurs in the moving unit during scanning due to the reactive force that the pinion gear receives from the rack teeth and affects the quality of a read image in some case. Under the circumstance, a technique of suppressing such wobbling has been proposed (for example, Japanese Patent Laid-Open Nos. 2008-15331 and 2012-83457).
Japanese Patent Laid-Open No. 2008-15331 discloses a technique of suppressing wobbling by devising the position of a pinion gear and using the biasing force of a compression coil spring. Japanese Patent Laid-Open No. 2012-83457 discloses a technique of suppressing wobbling by engaging a concave engaging portion with a convex guide member. The concave engaging portion has two slide surfaces which form inclined surfaces.
An arrangement configured to suppress wobbling by biasing a carriage against a guide member by a compression coil spring and the like leads to an increase in the number of components, as disclosed in Japanese Patent Laid-Open No. 2008-15331. If two slide surfaces form inclined surfaces as disclosed in Japanese Patent Laid-Open No. 2012-83457, a moving potion may straddle a guide member due to the reactive force that the pinion gear receives from the rack teeth.